Clinical trials are the primary mechanism by which new approaches to cancer treatment can be evaluated, yet only a very small proportion of eligible cancer patients are offered the opportunity to participate in clinical trials, and fewer actually become enrolled. Low accrual results in slower progress in developing and disseminating effective treatments as well as less generalizable and more costly studies. It is critical that the cancer research community take immediate steps to improve enrollment, yet little data currently exist to systematically guide the development of cost-effective interventions. The immediate goal of the study is to test a generalizable intervention to increase clinical trials accrual. The long term goal is to better understand the recruitment and enrollment process and where the greatest opportunities for enrollment are lost in order to strategically identify areas for future interventions. Our specific aims are to: (1) Evaluate in a cluster randomized trial the effectiveness of an outreach and education intervention consisting of letters combined with tailored telephone counseling by a nurse educator to increase enrollment in cancer clinical trials compared to standard trial recruitment procedures. The intervention will be tailored to patient language (English and Spanish), ethnic and cultural background, knowledge, attitudes and beliefs about clinical trials. We hypothesize that the intervention, will increase enrollment among eligible patients compared to standard recruitment procedures. (2) Assess where in the clinical trials recruitment process the greatest proportion of patients are lost to enrollment and develop empirically based estimates -- by age, gender, and race/ethnicity - of the proportion of potentially eligible patients who are offered and who enroll in cancer clinical trials. (3) Determine the most strategic places in the recruitment process for future interventions to improve recruitment to cancer clinical trials. We will test this intervention using multiple ongoing cooperative group trials for various cancers. The study sample will consist of 3700 patients, potentially eligible for these trials, as identified through automated data systems. In addition to collecting data on the proportion of potentially eligible patients who are offered and enroll in designated trials in the intervention and usual care groups, we will conduct surveys with patjents and oncologists to assess the effectiveness of the intervention and the major reasons for enrollment and lack of enrollment in clinical trials.